Add a "fork" of musl as //fusl.

fusl/src/passwd/getpwent_a.c

Index: fusl/src/passwd/getpwent_a.c
diff --git a/fusl/src/passwd/getpwent_a.c b/fusl/src/passwd/getpwent_a.c
new file mode 100644
index 0000000000000000000000000000000000000000..d1b4b53ce2008234ea37a4e5cfe5e78f5456142f
--- /dev/null
+++ b/fusl/src/passwd/getpwent_a.c
@@ -0,0 +1,54 @@
+#include "pwf.h"
+#include <pthread.h>
+
+static unsigned atou(char **s)
+{
+	unsigned x;
+	for (x=0; **s-'0'<10U; ++*s) x=10*x+(**s-'0');
+	return x;
+}
+
+int __getpwent_a(FILE *f, struct passwd *pw, char **line, size_t *size, struct passwd **res)
+{
+	ssize_t l;
+	char *s;
+	int rv = 0;
+	int cs;
+	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
+	for (;;) {
+		if ((l=getline(line, size, f)) < 0) {
+			rv = ferror(f) ? errno : 0;
+			free(*line);
+			*line = 0;
+			pw = 0;
+			break;
+		}
+		line[0][l-1] = 0;
+
+		s = line[0];
+		pw->pw_name = s++;
+		if (!(s = strchr(s, ':'))) continue;
+
+		*s++ = 0; pw->pw_passwd = s;
+		if (!(s = strchr(s, ':'))) continue;
+
+		*s++ = 0; pw->pw_uid = atou(&s);
+		if (*s != ':') continue;
+
+		*s++ = 0; pw->pw_gid = atou(&s);
+		if (*s != ':') continue;
+
+		*s++ = 0; pw->pw_gecos = s;
+		if (!(s = strchr(s, ':'))) continue;
+
+		*s++ = 0; pw->pw_dir = s;
+		if (!(s = strchr(s, ':'))) continue;
+
+		*s++ = 0; pw->pw_shell = s;
+		break;
+	}
+	pthread_setcancelstate(cs, 0);
+	*res = pw;
+	if (rv) errno = rv;
+	return rv;
+}